The long-term objective of understanding and controlling infantile amnesia will be pursued by continued focus on special dispositions of the infant rat for stimulus selection. This topic is to be studied in the relatively broad framework that incorporates three classes of hypothetical processes associated historically with the ontogeny of knowledge acquisition: differentiation and encoding, integration and organization, and maintenance and expression. In the first category the proposal is to test the notion that infant animals are particularly susceptible to encoding in terms of net intensity, assess the influence of early experience on transfer of conditioning between stimulus compounds and single elements, or vice versa, and identify which attributes of stimuli are actually encoded by infant (and older) animals. To investigate integration and organization, tests at several ages will focus on stimulus-stimulus learning involving a variety of sensory modalities. Of particular interest is the role of inter- and intramodal similarity between stimuli to be learned and the effect of temporal disparity in the presentation of these stimuli. Additional tests will assess the impact of configuring and backward conditioning on integration and organization at different ages. Tests of maintenance and expression will consider both the characteristics of infantile forgetting and the alleviation of such forgetting. For the former there will be tests of age-related differences in retention of incidental vs. target memories, and selected tests involving overshadowing, latent inhibition and sensory preconditioning to help determine whether the encoding disposition during infancy or that at testing (when older) will prevail in determining what is remembered about infancy. Finally, to investigate the alleviation of the forgetting of infantile learning we will test prior cueing treatments and the effects of the distribution of such treatments, the interval between conditioning and prior cueing, and that between prior cueing and test. Alleviation of forgetting by distinctive context will be studied, and the implicit reactivation paradigm will be used to determine how infantile encoding of a particular stimulus affects integration and organization of that stimulus with another at an older stage. Grant=P30CA33572 The Cancer Research Center at the City of Hope is a clearly-defined organizational entity within the City of Hope which brings together in horizontal fashiod the cancer-related elements from each Department and Division. The specific aims of the Cancer Center are to: -Stimulate collaborative research interactions between basic science and clinical investigators and between research groups in different areas of investigation. -Facilitate and enhance established interdisciplinary programs in basic and clinical research. -Develop and support core research facilities which improve the effectiveness and the interdisciplinary nature of the Center's research programs. -Support the development of new investigators and/or new programs of high scientific merit. During the past five years, the Cancer Center at the City of Hope has also continued to mature; its research programs have been extensively re- evaluated, focused, and expanded where appropriate after both external and internal review. A new Director and Associate Directors have been appointed. With the assistance of Core Grant support substantial new Core Facilities also have been developed to meet the needs of the Cancer Center membership. A central mission of the Cancer Center, to facilitate strong interactions between the basic and clinical sciences at the City of Hope, has been realized further with the funding of Program Project-type awards in four of the six Cancer Center Programs. In this application we are requesting support for staff; scientific programs in Molecular Biology, Cell and Tumor Biology, Immunology, Virology, Hematologic Malignancy, and Clinical and Experimental Therapeutics; fifteen shared resources; and developmental and administrative funds to carry out the specific aims of the Cancer Center.